Workstation Design Ergonomic Design Considerations Productequipment Job aids
Workstation Design • Ergonomic Design Considerations • Product/equipment • Job aids • User selection • Training of user ISE 311 1
Example 1 ISE 311 2
Example 2 BEFORE ISE 311 3
Example 3 ISE 311 4
Example 4 ISE 311 5
G 1: Avoid Static Loads and Fixed Work Postures • Static load increases systolic and diastolic blood pressure. • Metabolic wastes accumulate in the muscles. • Consider increasing recovery time. ISE 311 6
Static loading • Standing – Shoes affect center of gravity and forward bending moment. – Hard floors cause standing fatigue and increase heart rate. – Have hips parallel to the floor. – Provide bar rail to vary work posture. ISE 311 7
Static loading • Falls – Slips and falls are a major cause of unintentional injury deaths and have annual direct cost/capita of $50– 400. – Causes of falls: – Slips: unexpected horizontal foot movement – Trips: restriction of foot movement – Stepping-on-air: unexpected vertical foot movement ISE 311 8
Static loading • Solutions for Falls – Prevent the fall: – Use well-designed ladders, scaffolds, and ramps properly. – Provide safe steps. – Use three-contact rule. – Provide good friction and reduce lubricants. – Reduce the consequences of the fall: – Interrupt the fall. – Soften the impact. ISE 311 9
Static loading • Head Weight – – ISE 311 The head weighs about the same as a bowling ball. Keep the line of sight below the horizontal. Maintain forward head tilt of 10º-15º Avoid backward and sideward tilts. 10
Source: Boeing Company, http: //www. boeing. com/aboutus/environment/lead_ergo. htm ISE 311 11
Static loading • Hands/Arms – An arm weighs about 4. 4 kg. – Avoid using the hand to hold up a tool or work piece. – Avoid working with elevated hands. – Support the arms on the work surface or chair arms. – Consider using magnification. ISE 311 12
G 2: Reduce Musculoskeletal Disorders • Set the work height at 50 mm below the elbow. • Don’t bend your wrist. • Don’t lift your elbow. • Don’t reach behind your back. • Follow guidelines for hand arm motions. ISE 311 13
Source: Boeing Company, http: //www. boeing. com/aboutus/environment/lead_ergo. htm ISE 311 14
G 3: Set the Work Height at 50 mm Below the Elbow • Work height is defined in terms of elbow height. • Optimum height is slightly below the elbow. • Optimum height from the elbow is the same for sitting and standing. • Work height is not table height. ISE 311 15
VDT Workstations • Key items: screen, keyboard, document, eyes, hands • Workstation furniture must be adjustable. • Locate the primary visual element first: ahead of the eye, perpendicular to the line of sight. • Train the operator in adjusting the equipment. • Provide a wrist rest. ISE 311 16
VDT Workstations ISE 311 17
G 4: Furnish Every Employee with an Adjustable Chair • The cost of an adjustable chair is very low compared to labor cost. • Allow users to try chairs in their specific jobs. • Buy chairs that are easily adjustable. • Train people in proper adjustment. • Chair Design – Seats – Backrests – Armrests – Legs/pedestals ISE 311 18
Examples ISE 311 19
G 5: Use the Feet as Well as the Hands • The leg is slower and less dexterous than the hands. • The legs can provide 3 times the power of the arms. • Use pedals for power and control. ISE 311 20
G 6: Use Gravity; Don’t Oppose It • Make movements horizontal or downward; avoid lifting. • Consider using the weight of the body to increase mechanical force. • Use gravity to move material to the work. • Use gravity as a fixture. • Use gravity in feeding and disposal. ISE 311 21
G 7: Conserve Momentum • Avoid unnecessary acceleration and deceleration. • Use circular motion for stirring and polishing. • Follow through in disposal motions. • Eliminate grasping motions by providing lips, rolled edges, and holes. • Avoid transporting weight in the hand. ISE 311 22
G 8: Use 2 -Hand Motions Rather Than 1 -Hand Motions • Cranking with 2 arms is 25% more efficient than with one. • Using 2 hands is more productive despite taking more time and effort. • Don’t use the hand as a fixture. ISE 311 23
G 9: Use Parallel Motions for Eye Control of 2 -Hand Motions • Minimize the degree of spread rather than worry about symmetry. • Estimate the cost of eye control with predetermined time systems. • Parallel vs symmetrical motions BC B C A D Parallel motions ISE 311 • Shoulder moves • Easy eye travel DD C C B B A A Symmetrical motions • Shoulder steady • Difficult eye control 24
G 10: Use Rowing Motions for 2 -Hand Motions • Alternation causes movement of the shoulder and twisting of the torso. • Alternation causes higher heart rates. • Rowing motions are more efficient and provide greater power. ISE 311 25
G 11: Pivot Motions About the Elbow • Motion time is minimized with motion about the elbow. • Cross-body movements are more accurate than those about the elbow. • Physiological cost is lower for movements about the elbow. ISE 311 26
G 12: Use the Preferred Hand • The dominant hand is: – – 10% faster for reach-type motions More accurate than the non-dominant More exposed to cumulative trauma 5% to 10% stronger • Work should arrive from the operator’s preferred side and leave from the nonpreferred side. ISE 311 27
G 13: Keep Arm Motions in the Normal Work Area • • Avoid long benches. Use swingarms and lazy Susans. For high use, keep it close. Remember the arm pivots on the shoulder, not the nose. • The shoulder is very sensitive to small changes in workplace layout. ISE 311 28
“Windshield Wiper” Pattern ISE 311 29
G 14: Let the Small Person Reach; Let the Large Person Fit • Design so most of the user population can use the design. • Jobs must be designed for both sexes. • Multiperson use of equipment and stations is becoming more common. • Civilian industrial population data are not the same as military data. • International populations be a consideration. • The proportion to exclude depends on the seriousness of designing people out and the cost of including more people. ISE 311 30
Ways to Exclude Few • One size fits all • Multiple sizes • Adjustability ISE 311 31
- Slides: 31